Chevrolet Suburban Radiator Fluid Change

I have a 2009 Chevrolet Suburban 5.3L flex fuel I want to
change the radiator fluid. I bought one gallon of prestone
dexcool extended life 50/50 prediluted antifreeze/coolant, I
read online that I need probably 4 gallons because it holds
16-17 quarts. My question is how many gallons do I
actually need if I am buying the prediluted antifreeze and if
I'm wanting to drain out all the fluid clean it and replace it
with all new fluid. So this 50/50 mixture means I use only
this no water right? Also I read that I need to clean it before
adding the new fluid how would I clean it just take off the
cap and put the water hose in the top opening  while it
drains out the bottom leave the drain plug undone and do
this until water coming out the bottom is clear or close the
drain plug, put hose in fill up with water then drain and
repeat or what? It also says to bleed it, what exactly does
this mean..so I Leave the radiator cap off, turn on engine,
and let it run until the radiator bleeds out air. Probably takes
between 15 and 20 minutes to bleed all air out... do I still do
this if I'm draining all the fluid and replacing it all with new
fluid? I also read something that says cycle and Burp the
system??... So my last question is do I really need to do this
if so how?.. do I just  take off the radiator cap and fill with
the new antifreeze/coolant after I've drained and flushed
out the current/old fluid? It says after I fill it with the new
fluid to start the engine increase the truck's engine speed
to 2,000 to 2,500 rpm, and hold it there until the engine
reaches operating temperature -- about halfway up the
temperature gauge. Allow the engine to idle for about three
minutes and shut the engine off. When engine is cool to the
touch. Loosen the coolant overflow cap add 50-50
premixed Dex-Cool coolant to the coolant overflow
reservoir until the level reaches the "Full Cold" area on the
reservoird and done!! Then says While you let it cool it
should draw all fluid out of reservoir since you replaced the
cap before starting engine. You can also manually drain the
reservoir fill system with water then drive around with the
heater on to flush water thru the system. Come back, let
the truck cool, drain the water out, then fill it back up with
50/50 dexcool/water and I'm done...
How do I make sure to get all 16-17 quarts of current fluid
out and out ot reservoir or whatever ..

Please can someone give me detailed steps on how to
flush/change the radiator fluid in my 2009 chevrolet
suburban 5.3L flex fuel.. dont worry im having my mechanic
friend do it for me I just want to know exactly how and what
needs to be done so I can make sure he does it correctly!